碳酸盐岩储层类型测井定量评价方法及其对油田开发的意义

Log Interpretation Method for Water-flooded Layer with Obvious Heterogeneous Reservoir Character in K Oil Field, Central Asia

伊拉克H油田具有含油层系众多、储层巨厚、非均质性较强的特点。本文对伊拉克H油田碳酸盐岩储层类型的测井定量评价方法和划分方案进行了探索。在分析大量资料的基础上,运用常规测井和伽玛能谱测井资料约束全井眼电成像数据的定量计算,提出孔洞发育指数Dv以及裂缝发育指数Df,进而制定碳酸盐岩储层类型分类三角图版,对H油田碳酸盐岩储层类型进行详细划分,并初步探索了储层类型和产能的对应关系。最后阐述了该定量评价方法在油田开发井网部署中的重要意义。

Water flooded layers with sedimentary rhythm have typical log characters, except for complex rhythm. Koil field of Central Asia has several characteristics: sand grain is relatively fine, reservoirsheterogeneous character isobvious, oil viscosity is high and water flooding is serious.On the plane,reservoirs with strong heterogeneity are distributed in strips along the provenance. Vertically, as the A/S increases, the reservoir heterogeneity becomes stronger. The sandstone reservoir of K oil field is typical in Central Asia. Its pore structure is complex, and the correlation between porosity and permeability is low. As a result, it is difficult to obtain a relatively accurate permeability. Therefore, it is important to perform reasonable reservoir classification before evaluation of the flooded layer.In the resistivity-oilcolumn height cross plot of hundreds of original oil layers, the distribution characteristics of the reservoir can directly reflect the quality of the pore structure(porosity, permeability).Based on this, using the core andreconstructedcapillary pressure curve, K oilfield reservoirs can be classified into three grades on the crossplot. grade Ⅰ is mainly fine sandstone that deposits in distributary channel; grade Ⅲ is mainly argillaceous sandstone that deposits in mouth bar; grade Ⅱ is mainly silt that deposits in both distributary channel and mouth bar. On the crossplot, multivariate regressions are performed for each type of reservoir so that the disperse points are gathered into strips, thereby obtaining several key factors that determine the resistivity of the original reservoir.The performed resistivity-oil column chart can be used directly for the qualitative identification of flooded layers.Furthermore, the original resistivity of the water-flooded layer can be inverted, and Fw can be calculated by combining the relative permeability data to achieve a quantitative evaluation of the water-flooded layer.In addition, a simple method for reservoir classification is proposed only using conventional log data. After all, the applicationin 34 new wells showed that the coincidence rateof Fw is 85.3%.